1. Field of the Invention
The present invention relates to a method for sensing touch pressure and a digital device using the same, and more particularly, to a method for sensing touch pressure on a digital device by using the image data detected by a camera unit.
1. Discussion of the Related Art
Touch screens are widely used as a mean detecting users' input on digital devices. A touch screen is used to detect coordinates of a touch input directly on the screen, and generally, comprises a display unit and a touch panel, which are combined in a digital device. Users may perform touch inputs on a display object on a touch screen, and may operate the corresponding display object intuitively.
Common techniques for implementing a touch screen are a resistive type and a capacitive type. First, the resistive touch screen is in a form of several layers (screens) stacked on a display unit. For example, the outmost layer (where hands and pens contact) is a layer of soft and scratch-resistant material, and the next layer plays a shock-relieving role. Then, two sheets of transparent conductive layer, which detects inputs, are placed in sequence. If a user presses the screen, two sheets of transparent conductive layer get to contact each other to change electric current and resistance. The resistive touch screen may detect the change to determine horizontal and longitudinal coordinates of the user input. Therefore, the resistive touch screen is capable of precisely detecting touch inputs from a user's finger as well as auxiliary tools such as a stylus. However, compared to the capacitive touch screen, the resistive touch screen has some limitations, including slow response and low display quality due to several layers.
Next, the capacitive touch screen detects micro current flowing in a human body. In short, the whole screen is coated with conductive material to let electric current flow continuously. If a user's finger touches the screen, electrons flowing on the screen are attracted to the touch point. Then, the capacitive touch screen detects the touch input through a sensor in the corner of the touch screen. The capacitive touch screen has several advantages, including fast response and good display quality, as it is a screen coated with conductive material. However, there are also several limitations in the capacitive touch screen. For example, a finger or an exclusive stylus for a capacitive type screen should be used for the operation.
Meanwhile, additional devices are required in order to sense user's touch pressure on traditional touch screens. For example, touch pressure may be sensed only when a stylus connected to the digital device is equipped with pressure-sensing means and the stylus is used for performing touch inputs.